JPS641479Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a carburetor for supplying and controlling fuel to an engine, and in particular to a carburetor choke valve for forming a rich air-fuel mixture when starting an engine.

Prior Art The exhaust valve of such a carburetor needs to supply a thin air-fuel mixture compared to the initial explosion after the engine has exploded for the first time during startup, and for this purpose, a relief window is provided in the exhaust valve. However, there is a device in which a relief valve is disposed corresponding to this relief window, and the relief window is elastically biased to a closed state by a relief valve spring.

Problems to be Solved by the Invention According to the conventional chock valve of a carburetor, when starting the engine by keeping the chock valve in a fully closed state, the relief valve does not close at the time of the engine's first explosion. , The relief window is held closed by the spring force of the relief valve spring, and since both the relief valve and the relief valve are fully closed, a rich mixture can be supplied to the engine at the time of the engine's first explosion. It is. When the engine reaches a complete explosion following the first explosion, the rotation of the engine increases compared to the initial explosion state, and as the engine rotation increases, the negative pressure in the intake tract increases. Due to this increase in negative pressure, the relief valve opens the relief window against the spring force of the relief valve spring.

Therefore, air is introduced through the relief window to reduce the negative pressure acting on each fuel nozzle opening in the intake duct, and as air is introduced as described above, the air-fuel mixture is automatically diluted in the event of a complete explosion. It is something that can be done.

According to the choke valve of a conventional carburetor that performs this function, the choke valve is kept fully open after the engine has started, and in this state, the relief valve is closed due to engine vibration or pulsating flow in the intake tract. This vibration may cause problems in the durability of the relief valve rotation support, relief valve spring, and relief valve itself.

In order to suppress the vibration of the relief valve, this vibration can be suppressed by increasing the strength of the relief valve spring, but due to the opening characteristics of the relief valve at the time of a complete explosion, it is difficult to select a relief valve spring based on the balance with vibration. It was something.

Means and action for solving the problems The valve of the present invention for the carburetor was designed in consideration of the above points, and is a highly durable valve that allows the opening characteristics of the relief valve to be set optimally and prevents the relief valve from vibrating. For this purpose, when the relief valve is in a fully open state and the relief valve closes the relief window, the relief valve is held between one side of the relief valve and a fully open stopper provided in the intake passage. This prevents vibration of the relief valve and choke valve.

Embodiment Hereinafter, an embodiment of the choke valve of the carburetor according to the present invention will be described with reference to the drawings.

Reference numeral 1 denotes a carburetor body in which an intake passage 2 passes through and a ventilary portion 2A is provided in the middle part of the intake passage 2, and a float chamber body (not shown) is provided at the lower part of the carburetor body 1. is formed, and the fuel supplied from the fuel flow path is controlled by the float, float valve, and valve seat to form a constant liquid level in the float chamber. A choke shaft 3 rotatably supported by the carburetor main body 1 is disposed in the intake passage 2 on the upstream side of the ventilator portion 2A (to the left side in the figure from the ventilator portion 2A). A plate-shaped chiyoke valve 4 for opening and closing the channel 2 is attached with screws or the like, and a relief window 5 is bored through the chiyoke valve 4. A relief valve 6 that opens and closes the relief window corresponding to the relief window 5 is arranged on one side surface 4A of the chiyoke valve 4. That is, 7 is a support shaft installed upright on the relief valve 4, a shaft 8 is arranged between both the support parts 7, 7, and one end of the relief valve 6 is held by this shaft 8 and is arranged so as to be rotatable. On the other hand, the other portion has a sufficiently large diameter laterally than the relief window 5 so as to keep the relief window 5 in a closed state. Further, a full-open stopper portion 9 is provided in the intake passage 2, which comes into contact with one side 6A of the relief valve 6 that keeps the relief window 5 closed when the intake valve 4 is fully open.

The relief valve 6 is wound around a shaft 8, and has one end locked to the relief valve 4 and the other end locked to the relief valve 6. A pressure force for closing the relief window 5 is applied to the relief valve spring 10. It is something that is energized. In addition, one end of 11 is submerged under a certain liquid level in the float chamber, and the other end is connected to the intake passage 2.
It is the main nozzle as a fuel system that opens into A,
12 is the intake path 2 downstream from the ventilate portion 2A.
This is a throttle valve attached to a throttle shaft rotatably supported within the throttle shaft. Further, reference numeral 13 denotes a chiyoke lever provided at the end of the chiyoke shaft 3.

Next, its effect will be explained.

First, when starting the engine, the choke lever 13 is rotated to rotate the choke shaft 3, and the choke valve 4 is opened to the intake passage 2.
In this state, the relief valve 6 is pressed against one side surface 4A of the choke valve 4 by the spring force of a relief valve spring 10, thereby holding the relief window 5 in a closed state.
When the engine is started, the intake passage 2 is opened by the choke valve 4.
Since the yoke valve 4 is held in a fully closed state, a large negative pressure is generated in the intake passage 2 downstream of the yoke valve 4, which causes a large amount of fuel to be sucked out from each fuel nozzle. In addition, since the air flow rate through the intake passage 2 is restricted, a rich air-fuel mixture can be supplied and the engine can immediately start firing.

When the engine completely explodes after the first explosion, the engine speed increases compared to the initial explosion state, so the intake passage 2
The negative pressure inside the intake tract increases, and due to this increased negative pressure, the relief valve 6 is acted upon to open the relief window 5, and is relieved against the biasing force of the relief valve spring 10 in the closing direction. window 5
to open. Therefore, as the air flow rate flowing through the intake passage 2 is increased, the negative pressure applied to each fuel nozzle hole is weakened, and as the air flow rate is increased, the air-fuel mixture is automatically diluted.

The setting of the diluted mixture concentration at the time of complete explosion can be freely adjusted by the size of the relief window 5 and the spring force of the relief valve spring 10.

When the engine has passed through the complete explosion state and the starting state of the engine is completed, the engine lever 13 is rotated to fully open the engine valve 4 as shown in FIG. 2. At this time, the relief valve 6 is not easily subjected to force in the opening direction due to the negative pressure in the intake passage 2, so the relief window 5 is held in the closed state by the spring force of the relief valve spring 10. The other side surface 6B is in contact with one side surface 4A of the chiyoke valve 4.

On the other hand, one side 6A of the relief valve 6 is brought into contact with a fully open stopper portion 9. Thus, the relief valve 6 is held between the one side surface 4A of the choke valve 4 and the fully open stopper part 9.

Therefore, even if the engine is operated under such conditions and the relief valve 6 is subjected to vibrations generated in the engine and the pulsating flow through the intake passage 2, the relief valve 6 is securely in contact with the full-open stopper portion 9 and will not vibrate. As a result, no wear will occur due to vibration in the relief valve 6, shaft 8, and relief valve spring 10, and a carburetor choke valve with excellent durability can be provided.

In addition, the spring characteristics of the relief valve spring 10 are determined simply by considering the opening characteristics of the relief valve 6, and there is no need to consider the suppressing effect of the relief valve 6 due to vibrations, etc., thereby obtaining a carburetor choke valve with excellent starting performance. It is something that can be done.

Effects of the invention As described above, according to the chiyoke valve of the carburetor according to the present invention, the chiyoke valve is arranged on the chiyoke shaft rotatably supported on the carburetor body,
A relief window is bored in the chiyoke valve, and a relief valve that controls the opening and closing of the relief window by the negative pressure generated in the intake passage is arranged in correspondence with the relief window, and a full opening stopper is installed from the carburetor body in correspondence with the relief valve. Since the relief valve is provided with a protruding part, the relief valve is securely fixed by the fully open stopper part when the check valve is fully opened. This improves the wear resistance of not only the relief valve but also the parts that make up the check valve, resulting in excellent durability. Furthermore, since the spring force of the relief valve spring can be set to a spring force that takes only the opening and closing characteristics of the relief valve into consideration, it is possible to improve the startability of the engine.

[Brief explanation of the drawing]

The drawings show an embodiment of the choke valve of the carburetor according to the present invention, and FIG. 1 is a cross-sectional view thereof, and FIG. 2 is a longitudinal sectional view taken along the line of FIG. 1. 1... Carburetor body, 2... Intake path, 3... Chiyoke shaft, 4... Chiyoke valve, 5... Relief window, 6... Relief valve, 9... Fully open stopper part, 10... Relief valve spring .

Claims (1)

[Scope of Claim for Utility Model Registration] A tire yoke shaft is provided within the intake duct on the upstream side of the ventilate portion of the intake duct passing through the carburetor main body, and which traverses the intake duct and is rotatably supported on the carburetor main body. In the tire valve of a carburetor, the valve shaft is provided with a plate-shaped valve for controlling opening and closing of the intake passage;
and a plate-shaped relief valve 6 which is disposed on one side 4A of the chiyoke valve 4 and controls opening and closing of the relief window 5 by the negative pressure generated in the intake passage 2; When the relief valve 4 is fully opened, the full-open stopper part 9 contacts the one side surface 6A of the relief valve 6 that holds the relief window 5 closed.
and a fully open stopper part 9.